Research in this laboratory is centered around solution studies on the structure and dynamics of proteins, protein-protein complexes and protein-nucleic acid complexes using multidimensional NMR spectroscopy, and on the development and application of novel NMR and computational methods to aid in these studies. Particular emphasis is being placed on complexes involved in signal transduction and transcriptional regulation, and on AIDS and AIDS-related proteins. Recent accomplishments include the extension of the applicability of the NMR method to structures larger than 40 kDa. Examples of methodological developments include the panoply of 3D and 4D heteronuclear NMR experiments that have been developed at the NIH and are essential for studying larger proteins whose overlapping resonances pose a formidable problem; methods that make use of anisotropy of the alignment tensor (e.g. residual dipolar couplings measured on macromolecules dissolved in dilute liquid crystalline media such as the nematic phases of rod-shaped virus particles) or the diffusion tensor (for highly non-spherical molecules) to provide long-range orientational information that is not available from other NMR parameters that rely entirely on close spatial proximity of atoms; methods based on paramagnetic relaxation enhancement to obtain both structural information and to detect and characterize low population intermediates involved in macromolecular association; and the development of fast and efficient algorithms for the analysis of NMR spectra and for the computation of three-dimensional structures based on all available experimental NMR restraints. Recent developments include the first direct demonstration and structural characterization of transient low population intermediates iolved in both protein-DNA and protein-protein association.